Head loss due to Transitions and Fittings (Local loss) for InfoSWMM and SWMM5

Head loss due to Transitions and Fittings (Local loss)
Whenever flow velocity changes direction or magnitude in a conduit (e.g., at fittings, bends, and other appurtenances) added turbulence is induced. The energy associated with that turbulence is eventually dissipated into heat that produces a minor head loss, or local (or form) loss. The local (minor) loss associated with a particular fitting can be evaluated by
                                                                                                      
where   V         =          mean velocity in the conduit (m/s, ft/s)
                K         =          loss coefficient for the particular fitting involved.
The table given below provides the loss coefficients (K) for various transitions and fittings.
 
Table 3-3: Typical Minor Loss Coefficients
Type of form loss
K
Expansion
Sudden
D1 < D2
Gradual
D1/D2 = 0.8
0.03
D1/D2 = 0.5
0.08
D1/D2 = 0.2
0.13
Contraction
Sudden
D1 > D2
Gradual
D2/D1 = 0.8
0.05
D2/D1 = 0.5
0.065
D2/D1 = 0.2
0.08
Pipe entrance
Square-edge
0.5
Rounded
0.25
Projecting
0.8
Pipe exit
Submerged pipe to still water
1.0
Tee
Flow through run
0.6
Flow through side outlet
1.8
Orifice
(Pipe diameter
 /orifice diameter)
D/d = 4
4.8
D/d = 2
1.0
D/d = 1.33
0.24
Venturi (long-tube)
(Pipe diameter
 /throat diameter)
D/d = 3
1.1
D/d = 2
0.5
D/d = 1.33
0.2
Bend
90o miter bend with vanes
0.2
90o miter bend without vanes
1.1
45o miter bend
0.2
Type of form loss (continued)
K
Bend
45o smooth bend:
     (bend radius
 /pipe diameter)
r/D = 1
0.37
r/D = 2
0.22
r/D = 4
0.2
90o smooth bend
r/D = 1
0.5
r/D = 2
0.3
r/D = 4
0.25
Closed return bend
2.2
Sluice
Submerged port in wall
0.8
As conduit contraction
0.5
Without top submergence
0.2
Valve
Globe valve, fully open
10
Angel valve, fully open
5.0
Swing check valve, fully open
2.5
Gate valve, fully open
0.2
Gate valve, half open
5.6
Butterfly valve, fully open
1.2
Ball valve, fully open
0.1
       Source: Nicklow and Boulos (2005)

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